In the last third of pregnancy, the fetus starts to get ready to breathe after birth. It’s normal for the chest muscles to move in and out (as if the baby were breathing) while still in the womb. This can stop for long periods of time just a few seconds after the fetus is exposed to second-hand smoke.

Second-hand smoke is also linked to early birth (premature babies) and miscarriage and has many risks for children who are exposed to it regularly.